Self-Organizable Vesicular
Columns Assembled from
Polymers Dendronized with Semifluorinated Janus Dendrimers
Act As Reverse Thermal Actuators
- Publication date
- Publisher
Abstract
The synthesis and structural analysis of polymers dendronized
with
self-assembling Janus dendrimers containing one fluorinated and one
hydrogenated dendrons are reported. Janus dendrimers were attached
to the polymer backbone both from the hydrogenated and from the fluorinated
parts of the Janus dendrimer. Structural analysis of these dendronized
polymers and of their precursors by a combination of differential
scanning calorimetry, X-ray diffraction experiments on powder and
oriented fibers, and electron density maps have demonstrated that
in both cases the dendronized polymer consists of a vesicular columnar
structure containing fluorinated alkyl groups on its periphery. This
vesicular columnar structure is generated by a mechanism that involves
the intramolecular assembly of the Janus dendrimers into tapered dendrons
followed by the intramolecular self-assembly of the resulting dendronized
polymer in a vesicular column. By contrast with conventional polymers
dendronized with self-assembling tapered dendrons this new class of
dendronized polymers acts as thermal actuators that decrease the length
of the supramolecular column when the temperature is increased and
therefore, are called reverse thermal actuators. A mechanism for this
reversed process was proposed